The US was experiencing war fatigue -- having gone through World War II in the 1940s and the Korean War in the 1950s -- and rightfully didn't feel motivated to get involved in a battle which was basically meant as an exhibition match to show off to Russia what we were capable of. "We'll kick their Commie asses just like we'd kick yours."
When the US pulled out, genocide was committed against the Hmong people. For that alone, it would have been better if the US had prevailed. Crazy conservative John Wayne was right when he said that the US was once again fighting to prevent genocide. But when the war ended, no mention was made of the plight of Hmong people and the antiwar crowd celebrated a moral victory over the US.
I'd like to believe that most are unaware of the genocide. But when it's brought up, the blame is curiously placed on the US for covering it up rather than on the Vietnamese government for committing it. I suppose they'd find a way to spin the story and say that it never would have happened if the US had never chosen to fight. There's always a nonviolent solution and there's always a way to put the American government at fault for everything.
North Vietnam was the aggressor and we were fighting on behalf of the South, yet that made us the bad guy.